1. Technical Field
The present invention relates to a robot, a control device, and a robot system.
2. Related Art
In the related art, a robot including a robot arm is known. The robot arm includes a plurality of arms (arm members) coupled with one another through joint portions, in which, for example, a hand is attached as an end effector to the arm on the distal-most end side (the downstream-most side). The joint portions are driven by motors, and the arm rotates by the driving of the joint portion. Then, the robot grips, for example, an object with the hand, moves the object to a predetermined place, and performs predetermined work such as assembly.
Moreover, each of the motors is provided with an encoder that detects the rotation angle of the motor. A dedicated signal line is connected to each of the encoders, and the signal lines are connected to a control device that controls the robot.
JP-A-2004-70422 discloses, in a control device that controls a robot, to use multidrop connected encoders connected with one signal line common to the encoders. In the control device disclosed in JP-A-2004-70422, the number of motors and the number of control units (servos) that control the driving of the motors are set to be the same.
In the related-art robot, however, since the number of encoders and the number of signal lines are the same and the number of signal lines is large, the robot arm becomes thick. Due to this, work in a narrow space is difficult.
Moreover, in the control device disclosed in JP-A-2004-70422, since one signal line common to the encoders is connected thereto, the time required to transmit all of signals detected by the encoders is lengthened, thereby causing wasted waiting time in the control units. Due to this, the control of the robot is delayed.
Moreover, in the control device disclosed in JP-A-2004-70422, since the number of motors and the number of control units are the same and the number of control units is large, a circuit board of the control device is large, thereby increasing the size of the control device.